1. Field of the Invention
The present invention relates to a method and an apparatus for reproducing data from a data recording medium such as a CD-ROM and the like, which is provided tracks spirally on a disk, and more particularly to a method and apparatus for searching a target header, when a time information of the target header is given.
2. Description of the Related Art
In a CD-ROM, which is a data recording medium provided tracks spirally, a header composed of time informations for distinguishing data blocks is recorded and a sub-code consisting of a kind of informations is recorded. According to a drive for reproducing informations recorded on the CD-ROM, in response to an order from outside, on searching the target header address, a searching method, in which an address indicated by sub-code (sub-code Q included in it) being able to access rapidly in a drive without changing arrangement of data by de-interleave, was used. In other words, when a sub-code Q indicating an address equal to a target address is searched and an applicable sub-code Q can be searched, continuously, a header address is read out. By the way, in the CD-ROM, generally, there is a slight gap (error) between a time information of the header and a time information of the sub-code Q in a disk. Therefore, in case of that read out header address lags from the target header address, for example, the read out header address is positioned ahead of the target header address and the gap is smaller than previously set value, header address is read out on after another till the target header address will be found.
Also, in case that the read out header address is positioned ahead of the target header address in time and the gap is larger than previously set value or that the read out header address passes the target header address, an address of a sub-code Q corresponding to the gap is calculated and the sub-code Q corresponding to a calculated result is searched. And, when the sub-code Q corresponding to the calculated result is searched, a header address obtained soon after is read out.
However, to reading out in the CD-ROM reproducing device, an optical reading out head is adopted. Therefore, it needs predetermined time to be able to read out data recorded on tracks and, in case that the head moves onto another track, it takes long time for moving the optical reading head. Consequently, in case that, after searching a target sub-code Q and reading out a header address, again, searching a target sub-code Q and reading out the header address are executed, it takes long time from receiving a target header address to reading out a target header address, as a result, it brought about a problem that it needs long time to access data.